Hyperthermia is an elevated body temperature due to failed thermoregulation. On a cold day, elevated body temperature can help the body maintain an optimal temperature. On a hot day, however, hyperthermia can occur when the body produces or absorbs more heat than can be dissipated. When the elevated body temperatures are sufficiently high, hyperthermia is a medical emergency and requires immediate treatment to prevent disability or death.
Hypothermia is typically experienced during physical exertion in a hot environment. Wearing a personal cooling system can prevent or mitigate the risks of hypothermia in such conditions. Important factors to the selection of a personal cooling system are weight and convenience. Existing personal cooling systems that utilize heat pumps or cold packs are encumbering, and particularly so, during physical exertion. There continues to be a need for advances in personal cooling systems.